Canon IP8750 leaving black dots and scratch/dust marks?

[Pgachette]

I own two 8750’s and both of them are doing the same thing. I print about 20 sheets a day glossy paper and have never had this issue. Both printers have been fine since today. I will add pictures to the thread but these dots are darker black dots only amongst black spaces/area on printed page. They are random as I’ve printed many pages. Pages with no black ink used tend to come out a lot better.

also there are scratches or marks on the left side of the page, as if the printer head is catching on the return as it goes back and forth. Not sure at all.

I’ve cleaned the print head with the software and taken them out and cleaned both manually, can’t seem to not get the dots and scratch marks.

I’ve printed about 5000 pages + on these printers and this is first time it’s happened.

just want to know what things to look at and what possible could be the issue all of a sudden?

 

[Ink stained Fingers]

Do you see any strange effects on the nozzle check print ? - please post it here
Does the effect vary with the paper type or size ?

 

[Pgachette]

Do you see any strange effects on the nozzle check print ? - please post it here
Does the effect vary with the paper type or size ?

Nozzle check turns out perfect. I’ve even aligned the head manually and automatically to rule it out. I’ve tried deep cleaning everything. The paper type does not affect it it only happens with black solid colour on gloss paper. I don’t get the same with plain paper at all. Only thing I’ve done is cleaned heads manually but I’ve been told I could’ve damaged something in the head which would cause it to react like this. Could this be a symptom of wrongly cleaning the printer head? Not sure how it would cause scratching or dust if I’ve cleaned the contacts properly?

 

[Ink stained Fingers]

The printer uses a pigment black ink when printing on normal paper, and a photo dye black to print on glossy paper - that's controlled via the paper type selection in the driver.

The scratches have a circular shape, no relative movement of the printhead against the paper would cause this, I'm afraid that there is some scratchy dust on this paper - is it Canon Paper ? How is it packed ? Try to wipe it off with a piece of fine cloth - like microfibre, but it could very well be that the scratches are already there from prior movement of the sheets against each other.

I would assume as well that the black spots are a problem in the paper coating, try to print a solid cyan spot to compare if that would would make similar spots visible. .

 

[Engine-Number9]

Maybe some lint or dust that blocks the heads each time when printing?

 

[Ink stained Fingers]

Maybe some lint or dust that blocks the heads each time when printing?

The printhead performs a linear motion back and forth - I don't see how that can cause scratches with a circular shape